This disclosure relates generally to battery charging circuits for portable user devices.
Portable user devices (e.g., laptop computers, cameras, cell phones, PDAs, GPS units, music player devices, and other hand-held devices) can have batteries that need recharging. Typically, a user may recharge the batteries of portable user devices using AC adapters or other tethered charging systems. Although AC adapters or similar charging systems can be a useful means for a user to recharge the batteries of a user device, it may be difficult or impossible for a user to find a wall outlet at a given time. Additionally, a portable user device can have an adapter specific to the device. If a user wishes to be able to recharge the batteries of a multitude of portable user devices, a user may need to be in possession of a variety of adapters, which may prove difficult for a user to transport or store.
There is a need for a charger that is compatible with a multitude of portable user devices. Furthermore, there is a need for a charger which does not require access to a wall outlet for operation. Moreover, there is a need for a charger which can efficiently recharge the batteries of portable user devices.